Earthquake sensors detected Indianapolis explosion

Nov. 12, 2012

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Explosion in neighborhood on Indianapolis' Southsi...: A massive explosion was reported about 11 p.m. Nov. 10 at a residence off Stop 11 Road and Sherman Drive. Neighbors reported hearing the explosion from miles away. (Matt Kryger / The Star)

The explosion late Saturday that killed two people and damaged 80 homes on Indianapolis’ Southeastside was so strong it was detected on scientists’ earthquake sensors miles from the scene.

“We’re still sorting through the data . . . but it’s likely we picked up the sound wave, the boom triggered by the explosion,” said Michael Hamburger, a professor of geological sciences at Indiana University.

Hamburger cautioned that the above-ground blast late Saturday night can’t be compared to a typical underground earthquake, so there isn’t a Richter-scale number to measure the rumble that shook dishes and rattled picture frames miles from the blast site.

Nonetheless, the closest earthquake sensor to the blast — almost 30 miles away at Martinsville in Morgan County — detected a rumble in the ground at 11:08 p.m.

Two other sensors further away at Sheridan in Hamilton County and Milroy in Rush County picked up vibrations in the air about three minutes later, just enough time for the “airwave boom” to make its way to the test sites.

Hamburger said those two sensors are measuring barometric pressure and “infrasound subsonic” waves as part of a national earthquake experiment.

The same sensors in Martinsville didn’t detect the sound waves, but did detect the ground vibrations, he said.

It wasn’t the only rumble seismologists detected.

On Saturday afternoon, at 12:08 p.m., an actual earthquake was felt in parts of Indiana.

The U.S. Geological Survey website said the epicenter of the 4.3 magnitude earthquake was about 10 miles west of Whitesburg, Ky., near the Virginia border.